Filter media performance and

its influence on filtration results Experience, expectations and possibilities in vacuum and pressure filtration

Content

Introduction

Filter media design

Laboratory results

Scale up results

Final conclusion

Filter media selection

6 step guideline

Introduction

Questions a filter media user should raise:

How can the performance during vacuum or pressure filtration be positively influenced by

the filter media?

What is the influence of the filter media on filtration performance in cake filtration?

Is it possible to influence the filtration time by using the “right” filter media?

Which filter media parameters have to be taken in account?

Point out influences and parameters related to the filter media during

cake filtration process in pressure and vacuum filtration

Integrate findings in filter media design and in your process!

Filter media design

Filter media parameters that could

influence the filtration process:

Fabric construction (Weaving pattern)

Pore size, shape and pore distribution

Number of pores per cm2

Filter media air and liquid permeability

Resulting flow resistance

Suitability for the use on the filter equipment

Observe design influences in lab

Verification under working conditions

Content

Introduction

Filter media design

Laboratory results

Scale up results

Final conclusion

Filter media selection

6 step guideline

Laboratory results

Pressure nutsch filter test set- up:

Calcium carbonate CaCO3 (Omya 10H) with D50 = 15 µm

Suspension with 20% solid content

Pore size of filter media = 1.2 – 2.0 x D50 of CaCO3

Filter media with different weaving pattern, pore designs,

air permeabilities and pore count are observed

Laboratory tests are carried out under identical

conditions- variable parameter = filter media

Laboratory results – focus air permeability

Air permeability vs. filtration time - comparison of 2 DLW generations

y = -0.0502x + 94.994R² = 0.7748

y = -0.0319x + 78.869R² = 0.8601

50

60

70

80

90

100

110

0 100 200 300 400 500 600

filt

rati

on

tim

e (

s)

air permeability (l/(m2*s))

Air permeability vs. filtration time of different pore sizes and generations

DLW - Gen 2 DLW - Gen 3

Figure: Air permeability vs. filtration time of two generations of DLW

DLW constructions of 2 generations

Different air permeability

Significant influence of fabric design

Reduction of filtration time by 10 % from

Gen 2 to Gen 3

Air permeability is one indication, but not

the only selection criteria!

Laboratory results – focus on pore count

Air permeability vs. filtration time - focus only on 20µm pore size

DLW construction

Same average pore sizes

Similar air permeability

Different number of pores

Number of pores has a significant

influence on filtration time at a

comparable level of filtrate clarity

The higher the number of pores, the

shorter the filtration time

y = -0.0197x + 106.52R² = 0.8124

50

60

70

80

90

100

110

0 200 400 600 800 1000 1200 1400 1600 1800

filt

rati

on

tim

e (s

)

number of pores (1/cm2)

Pore count vs. filtration time of DLW generations comparing pore sizes

of 20µm

DLW - Gen 1 DLW - Gen 2 DLW - Gen 3

Figure: Number of pores vs. filtration time of DLW of the same pore size

Laboratory results – media resistance

Air permeabilty vs. filtration time - focus filter media resistance

DLW construction

Same average pore sizes

Similar air permeability

Different number of pores

Number of pores has a significant

influence on filtration time and resulting

filter cake and media resistance

Lower filter media resistance, shorter

filtration time

y = 0.0627x + 1.356R² = 0.9959

y = 0.0431x + 1.3821R² = 0.9937

y = 0.0489x + 0.8798R² = 0.9861

y = 0.0541x + 0.42R² = 0.99710

0.5

1

1.5

2

2.5

3

3.5

0 5 10 15 20 25 30

filt

rati

on

tim

e (

s)

/ q

ua

nti

ty o

f fi

ltra

te (

g)

quantity of filtrate (g)

Filter cake and filter media resistance of different DLW generations

with a pore size of 20µm

Gen 1 # 25

Gen 2 # 13

Gen 3 # 14

Gen 4 # 17

Figure: Filter media and filter cake resistance vs. filtration time

Conclusion

How to decrease filter media resistance, have the same particle

retention and improve throughput at the same time?

Ideally shaped pores for good particle retention and highest flow rate

Good media drainage to avoid micro liquid patches thanks the support and

drainage layer (Double layer weave fabrics)

High permeability (air and liquid due to the high pore number)

Increased number of pores per cm2

Appropriate filter media selection leads to shorter filtration time

and increases filtration efficiency

Conclusion

These findings were integrated in latest filter media developments

Verification of laboratory results under working conditions

Content

Introduction

Filter media design

Laboratory results

Scale up results

Final conclusion

Filter media selection

6 step guideline

Scale up- Zinc ore benefication

Starting position (Laboratory)

Improve filtration rate to cope with increased

slurry feed

Filtrate clarity shall be kept stable (≤ 1 g/l)

Moisture content target: less than 45%

Actions taken (Laboratory)

Carry out vacuum nutsch test

Analysis of current used filter media

Select alternative fabric to achieve the listed

targets

Result: Targets should be met with SEFAR

TETEX® DLW HD

Parameter filter test lab Unit

Test reference

Suspension

PSD D50 µm

Solid content g/l

Flocculant

Flocculant content g/l

Vacuum pressure mmHg

Filter media

Fitration capacity (m3/m2/h)

Test no.

Filtrate volume ml sec ml/ sec sec ml/ sec sec ml/ sec sec ml/ sec

10 0.3 40.0 0.3 40.0 0.3 40.0 0.3 40.0

20 0.5 40.0 0.5 40.0 0.5 40.0 0.5 40.0

30 1.0 20.0 1.0 20.0 1.0 20.0 1.0 20.0

40 1.5 20.0 1.5 20.0 1.5 20.0 1.5 20.0

50 2.0 20.0 2.0 20.0 2.0 20.0 2.0 20.0

60 2.5 20.0 2.5 20.0 2.5 20.0 2.5 20.0

70 3.0 20.0 3.0 20.0 3.0 20.0 3.0 20.0

80 3.5 20.0 3.5 20.0 3.5 20.0 3.5 20.0

90 4.0 20.0 4.0 20.0 4.5 20.0 4.5 10.0

100 5.0 10.0 5.0 10.0 5.5 10.0 5.5 10.0

110 6.0 10.0 6.0 10.0 6.5 10.0 6.5 10.0

120 7.0 10.0 7.0 10.0 7.5 6.7 8.0 6.7

130 8.0 10.0 8.0 10.0 9.0 5.0 10.0 5.0

140 10.0 5.0 10.0 5.0 11.0 5.0 12.0 5.0

150 12.0 5.0 12.0 5.0 13.0 5.0 14.0 5.0

Residual cake moisture

Solid content filtrate g/l0.77 0.73 1.01

0.75 0.95

450

SEFAR TETEX® DLW Single layer fabric

18.00 17.42 17.11 16.78Filtration rate av g (ml/ sec)

17.71 16.95

0.90

1.15 0.95

Details & Values

Vacuum Nutsch Test RDno.21/14

Jarosite slurry

74

131.8

FA 920

1 (450 g.floc/Tsolid)

11.02 10.38

0.90

Thickness of cake mm 1.10 1.20 1.00

%54.40 55.72 56.70 57.10

55.06 56.90

Test 1 Test 2 Test 1 Test 2

ml

Scale up- Zinc ore benefication

Results (Scale- up)

Filtration rate increased by 7%

Reduced cake moisture (4%) and reduced solid

content in the filtrate

Confirmation of the lab data during 40 production

days

A more stable filter belt in terms of lifetime (4000

hrs +) and elongation was provided

Conclusions (Scale- up)

Improved mechanical performance due the double

layer weave construction

One layer is mainly for the filtration and one layer

for the mechanical performance responsible

Scale up- Coolant filtration

Starting position (Laboratory)

Metal impurities in coolant increased (process

changed)

Utilized filter media needed to be adjusted

Improve particle retention (reduce load on

secondary filter)

Improve throughput (reduce number of filter

cycles)

Actions taken (Laboratory)

Analysis of current used filter media and

amount of particles in the coolant

Select fabric to reduce amount of particles in

the filtrate at similar flow rate as today

3. Particle size distribution of 'filtrate vessel' and of 'filt

er feed suspension'

6. Particle retention behavior of analyzed fabrics

Fig.1: particles filtrate vessel

Fig. 2 Particles 'filter feed suspension'

Fig. 3: Cake formation on reference fabric

Particle size distribution

Anzahl PartikelFlächenanteil Klassenfläche

Mittel ECD

Summenkurve

#

%

µm

0

0.00

0.00

0.00

439

3.24

2.78

3.24

136

8.01

8.52

11.25

63

8.25

14.37

19.50

35

11.21

20.22

30.71

27.00

14.55

26.28

45.25

15.00

12.68

32.90

57.93

4

4.65

38.60

62.57

4

5.96

43.70

68.53

Fig.5: Cake formation on alternative 2

3

5.95

50.48

74.48

2

5.06

57.02

79.54

1

2.90

61.00

82.44

2

8.06

80.41

90.50

1

5.50

84.06

96.00

1

2.00

131.12

97.69

1

1.80

154.03

100.00

16

4.Filtration trialsKunde:

Internal

Umgebung 21.6 °C , 32 %

Laborauftrag:1128

Datum: 24.10.2014

Filtergewebe:keine Vorbehandlung

Ausführer: DesTest Nr.

1

23

Suspension

KSS KundeKSS Kunde

KSS Kunde

Temperatur

RTRT

RT

Dichte theoretisch

2.72.7

2.7

Feststoffgehalt (%)

2020

20

Zeit in Sekunden Filtrationszeit, Kuchenbildungszeit114

122198

Entfeuchtungszeit

9090

90

Beobachtungen:Kuchenverhalten (Risse)

klebrigkompakt, klebrig kompakt, trocken

Kuchenablösung

3

22

Kuchendicke (cm)

0.30.5

0.6

Zeit in Sekunden Filtrationszeit, Kuchenbildungszeit112

140208

Entfeuchtungszeit

9090

90

Beobachtungen:Kuchenablösung

3

22

Kuchendicke (cm)

0.30.5

0.6

Filtratklarheit, Durchlass (g)

0.0960.034

0.014

Gew icht Kuchen nass (g)

10.2011.57

11.80

Filtrat (ml)

33.034.0

34.0

Resultat

Restfeuchte Kuchen (%)

21.917.2

16.4

Gew icht Kuchen trocken (g)

8.29.04

8.98

Feststoff in Filtrat (g)

0.0960.034

0.014

Konzentration Feststoff im Filtrat (g/ml)

0.00290.0010

0.0004

Porosität ?

0.16340.4466

0.5419

5.Cake release on different fabrics

Test Conditionen 2. Filtration

Test Conditionen 3. Filtration

6. Particle retention behavior of analyzed fabrics

Fig. 3: Cake formation on reference fabric

Fig. 4: Cake formation on alternative 1

Fig.5: Cake formation on alternative 2

Fig.6: particles in filtrate (g/ml)

Fig 6: Pressure increase versus filtration time

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

0

50

100

150

200

250

300

Dru

ck (

bar

)

Zeit (s)

Reference fabricAlternative 2Alternative 1

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

Restschmutzvergleich

Re

stsc

hm

utz

(g/

ml)

Refernce fabricAlternative 1Alternative 2

Scale up- Coolant filtration

Results(Scale- up)

Fines in filtrate reduced by 29%

Liquid throughput increased up to 66%

Lifetime of the filter belt increased

Conclusions (Scale- up)

Fabric with higher air permeability and different

pore structure created a higher resitance during

trials

Cake build- up time and overall resistance were

improved by different fabric design

Permeability is not sufficient to describe the

filter media properties

Square mesh fabric: Pressure increase to 0.6 bar-

achieved within 30 min. Throughput rate at 103m³

New double layer fabric: Pressure increase to 0.6 bar –

achieved within 90 min. Throughput rate avg. is at 119m³

Summary scale-up results

New filter media constructions offer additional benefits

Separation of function (filtration and drainage/

transport layer) creates significant advantages

Pore size and permeability are not sufficient to

describe the filter media properties

Additional information as pore count are needed

Content

Introduction

Filter media design

Laboratory results

Scale up results

Final conclusion

Filter media selection

6 step guideline

Final Conclusion

Media resistance and resulting cake resistance depending on

fabric construction, pore size, pore shape, pore count and media

permeability

Filter media design is one key element for a successful filtration

It is possible to enhance the filtration performance significantly

with

• Higher permeability

• Increased number of pores

• Improved pore shape

Filter media selection 6 step guideline

A high air permeability and a high number of pores results in a lower filter media resistance while still

keeping back the same amount of fines. The lower filter media resistance leads to shorter filtration time

and/ or better cake washing and drying behavior.

Paying attention to a key element means often reducing overall costs!

Check

chemical resistance

Check

temperature resistance

Check

mechanical properties

Check

suspension properties

Check

filtration capacity requirements

Check

equipment requirements

The versatile filter media manufacturer

Leading filter media manufacturers have to provide more than physical

filter media data

Application and process know- how is needed in order to define the most

suitable filter media solution for a specific filtration task

Sefar offers these services and helps its customers to enhance their

results

Thank you for your kind attention

For more information visit our booth

or check www.sefar.com

Laboratory Tests- utilized materials

Filter media - different generations of DLW (Double layer weave)

constructions with similar MFP and reference single layer fabrics

No. Material Filament

type

Weave

pattern

Pore size

MFP

(µm)

Pore count

(1/cm2)

Air

permeability

@ 200 Pa

(l/(m2·s))

Water

permeabilty

(l/(m2·s))

24 PP Mono-multi DLW - Gen 1 21 480 43 8

25 PP Mono-multi DLW - Gen 1 22 460 61 12

18 PP Mono-multi DLW - Gen 2 10 820 17 4

13 PP Mono-multi DLW - Gen 2 19 660 57 11

20 PP Mono-multi DLW - Gen 2 25 850 114 19

22 PP Mono DLW - Gen 2 32 780 178 28

19 PP Mono-multi DLW - Gen 3 25 1340 40 7

14 PP Mono-multi DLW - Gen 3 23 1640 70 13

21 PP Mono-multi DLW - Gen 3 33 1640 119 19

23 PP Mono DLW - Gen 3 38 1580 245 42

17 PET Mono-multi DLW - Gen 4 20 8890 203 35

16 PET Mono PRD 28 3450 657 117

15 PET Multi TWL 19 3220 251 44

Laboratory Tests - utilized suspension

Suspension - CaCO3 (Omya 10H), 20 % saturated

Figure : Particle distribution and particle characterization of CaCO3 suspension

Laboratory Tests- utilized equipment

Test equipment

Pressure nutsch @ rt

Filter area of 12.6 cm2

Max. cake height 25 mm

Pressure of 0.7 bar

Suspension volume 40 ml

Figure : Right: test set up – schematic (1), left: pressure nutsch test equipment

Filter media resistance RT and filter cake resistance rc were calculated as characterizing factor. It unifies all influences such as particle size and

distribution, pore shape, porosity and structure of filter cake and filter media. Both factors are calculated, analyzing the measured filtrate quantity over

time (1), (3).

RT = filter media resistance (1/m)

a = axis intercept a

A = filter area (m2)

Δp = pressure difference (Pa)

Η = viscosity liquid (Pa*s)

Laboratory results – focus air permeability

Air permeability vs. filtration time - focus on 20µm avg. pore size

DLW construction

Same average pore sizes

Different air permeability

Different number of pores

Air permeability is no significant

influence when comparing same

pore sizes

Number of pores is the only

difference and has to be taken in

account

50

60

70

80

90

100

110

0 50 100 150 200 250

filt

rati

on

tim

e (s

)

air permeability (l/(m2*s))

Air permeability vs. filtration time of DLW generations with the same

pore sizes - 20µm

DLW - Gen 1 DLW - Gen 2 DLW - Gen 3 DLW - Gen 4

Figure: Air permeability and filtration time at same pore size

y = 3E-07x + 60.51R² = 0.8583

0

20

40

60

80

100

120

0.E+00 2.E+07 4.E+07 6.E+07 8.E+07 1.E+08 1.E+08 1.E+08

filt

rati

on

tim

e (

s)

filter media resistance Rm (1/m)

filter media resistance vs. filtration time

Laboratory results for fabric selection

Filter media resistance vs. filtration time

Same average pore sizes

Improvement of filtration time by

choosing a media with lower

resistance

Lower resistance is achieved by

selection of a filter media with a

higher number of pores

Filtration can be enhanced

significantly by dedicated media

engineering (permeability, pore

count and shape)

Figure : Filter media resistance vs. filtration time